U.S. Pat. No. 4,612,345 (Hess, Sep. 16, 1986) relates to suspending agents of the hydroxypropyl methyl cellulose type and to a process for preparing vinyl chloride polymers by suspension polymerization of vinyl chloride wherein hydroxypropyl methyl cellulose ethers are used as suspending agents.
This patent provides new suspending agents of the hydroxypropyl methyl cellulose type for suspension polymerization of vinyl chloride which do not have the deficiencies of the known suspending agents of this type. This reference also provides new suspending agents of the hydroxypropyl methyl cellulose type for suspension polymerization of vinyl chloride which suspending agents are useful for increasing or controlling the porosity of the produced polyvinyl chloride particles.
U.S. Pat. No. 4,797,458 (Sharaby, Jan. 10, 1989) relates to polymers of vinyl halides having low molecular weight, good particle characteristics and improved melt flow. The polymers are made by aqueous polymerization utilizing an effective amount of a mercaptan as a chain transfer agent, wherein the mercaptan chain transfer agent is mixed with at least one material which is non-polymerizable with vinyl chloride and wherein non-polymerizable material is substantially insoluble in water and is miscible with said mercaptan to form a chain transfer composition. The chain transfer composition is added before the start of the polymerization while maintaining colloidal stability.
U.S. Pat. No. 4,471,096 (Sharaby et al, Sep. 11, 1984) relates to a process for the production of vinyl chloride polymers. It has been found that mercapto organic compounds having at least one beta-ether linkage are highly efficient chain-transfer agents in the production of vinyl chloride polymers that do not have the disadvantages of the previously known chain-transfer agents. These chain-transfer agents do not affect the color, odor, and other physical properties of the polymers and do not cause pollution problems.